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Seg 4: Order of the pins for the nixie tube and coding

Similarly, why do we know the order the pin? If we do not know the order of the pins, we do not know how to connect to the pins of nixietube. For example, if we want to display the digital number 5, how can we connect the dupon lines from the pins of nixie tube to the ports on the Arduino? To connect to the Arduino board rightly, we must know the connect rules.

re-know the nixie tube

We firstly know the pins of nixie tube from the followings in Figure 6-6.

Figure 6-6 Pins connection of nixie tube

As shown on the left subfigure of Figure 6-6, the digital number is labeled from the lower left by the counterclockwise, and the number of point is 5. All of the number is 1~10.

The letter label is marked from up to down by the clockwise. It is a~h, respectively, where the number of point is “h” as the last location.

Digital number 3 and 8 is the common port, which is the common anode or cathode. Figure 6-6 is the common cathode nixie tube; that is, all of the negative pins are connected a common port 3 or 8.

Coding of nixie tube

What is coding? To make the nixie tube display the designed digital number, we should let the LED to be conduction. For example, we want to display number 5 in Figure 6-6, how? Firstly, the polarity is must be right. In such experiment, the nixie tube is the common cathode. Thus, the common cathode should be connected to the GND port on the Arduino. Other pins must be corresponding to the ports on the Arduino to display the right digital number. This is coding. For example, in the letter view, if let the pins of a,c,d,f,g set as a high voltage level (or 1), and other pins is set as low level, (or 0), then, the corresponding segments would be light and digital number 5 can be displayed on the nixie tube. Since the decimal point “h” would not affect the display of digital number, it can be conducted or not. In this experiment, the decimal point is conducted. From the digital view, pins 2,4,5,7,9,10 are conducted, and the other remaining ones are not. Therefore, if we use binary code to express this segment, it can be coded as {0,1,1,1,0,1,1,1}. That is, there are two segments dark among of the eight segments in the nixie tube. Then, digital number “5″ can be displayed correctly. By this coding method, we can get other digital number coding, as shown in Table 6-2.

Table 6-2 Digital number coding scheme for the common cathode nixie tube

Arduino ports

Nixietube pins

0

1

2

3

4

5

6

7

8

9

4

1(e)

1

0

1

0

0

0

1

0

1

0

5

2(d)

1

0

1

1

0

1

1

0

1

1

6

4(c)

1

1

0

1

1

1

1

1

1

1

7

5(Dp)

1

1

1

1

1

1

1

1

1

1

8

6(b)

1

1

1

1

1

0

0

1

1

1

9

7(a)

1

0

1

1

0

1

1

1

1

1

10

9(f)

1

0

0

0

1

1

1

0

1

1

11

10(g)

0

0

1

1

1

1

1

0

1

1

Note that, to avoid the error of connection to Arduino, or convenience, we had better encode the digital number by one-defined rule. For example, in this experiment, let the digital ports on Arduino board correspond to the pins of nixietube for small to big (1~10). Certainly, there are many encoding schemes by following different ones’ habits. But the effect of display and the code is the same.